Coaxial contra-rotating propeller aerodynamic configuration design method based on tension distribution

Abstract

The invention provides a coaxial contra-rotating propeller aerodynamic configuration design method based on tension distribution, and belongs to the field of propeller design, and the method comprises the following steps: according to a front propeller tension distribution curve, basic data, an actual inflow angle of a front propeller and an induced pitch of the front propeller; the aerodynamic configuration of the front propeller of the coaxial contra-rotating propeller is obtained according to a single propeller design method; the induced speed of the front propeller is calculated according to the actual inflow angle of the front propeller and the induced pitch of the front propeller; according to the rear propeller tension distribution curve, the basic data, the induced velocity of the front propeller, the inter-propeller spacing factor and the inter-propeller blocking factor, the actual inflow angle of the rear propeller and the induced pitch of the rear propeller are obtained; according to the induced velocity of the front propeller, the actual inflow angle of the rear propeller, the inter-propeller spacing factor and the inter-propeller blocking factor, the resultant velocity of the rear propeller is obtained; according to the resultant velocity of the rear propeller, the chord length of the rear propeller is obtained, the rotation angle of the rear propeller is obtained according to the actual inflow angle of the rear propeller, experiments prove that the method is effective, and the aerodynamic configuration design precision is improved.

Description

Technical Field

[0001] The invention belongs to the field of propeller design, and in particular relates to a method for designing the aerodynamic shape of a coaxial counter-rotating propeller based on tension distribution. Background Art

[0002] The coaxial counter-rotating propeller is a special propeller configuration, which consists of two propellers installed coaxially and rotating in opposite directions. The two propellers are connected to the power unit through their own transmission systems. Since the two propellers rotate in opposite directions, the torques they generate cancel each other out, reducing the adverse effects on the aircraft or ship, and the two propellers working at the same time can generate greater thrust than a single propeller.

[0003] A coaxial counter-rotating propeller includes a front propeller and a rear propeller. In the aerodynamic shape design of a coaxial counter-rotating propeller, the aerodynamic shape of the front propeller is usually designed, and then the aerodynamic shape of the rear propeller is obtained through experience and manual fine-tuning. The aerodynamic shape of the rear propeller obtained in this way is inaccurate. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present application proposes a method for designing the aerodynamic shape of coaxial counter-rotating propellers based on thrust distribution. The method abandons the design scheme of designing the aerodynamic shape of the front propeller and then obtaining the aerodynamic shape of the rear propeller through fine-tuning. Instead, the aerodynamic shape of the front propeller is designed according to the thrust distribution curve, and the aerodynamic shape of the rear propeller is obtained according to the thrust distribution curve, the induced speed of the front propeller, the inter-propeller spacing factor and the inter-propeller blocking factor. Experiments have proved that the method is effective and the aerodynamic shape of the rear propeller obtained is more accurate.

[0005] In a first aspect, the present application proposes a method for designing a coaxial counter-rotating propeller aerodynamic shape based on tension distribution, comprising:

[0006] Obtaining a front propeller thrust distribution curve and a rear propeller thrust distribution curve of a coaxial counter-rotating propeller;

[0007] Determine the basic data of the coaxial counter-rotating propeller according to the design requirements of the coaxial counter-rotating propeller;

[0008] According to the front propeller thrust distribution curve and basic data, the actual inflow angle and induced pitch from the root of the front propeller blade to any section of the blade are obtained, which are recorded as the actual inflow angle and induced pitch of the front propeller;

[0009] According to the actual inflow angle of the front propeller and the induced pitch of the front propeller, the aerodynamic shape of the front propeller of the coaxial counter-rotating propeller is obtained according to the design method of a single propeller.

[0010] The induced speed of the front propeller is calculated based on the actual inflow angle of the front propeller and the induced pitch of the front propeller;

[0011] According to the rear propeller thrust distribution curve, basic data, the induced speed of the front propeller, the inter-propeller spacing factor, and the inter-propeller blocking factor, an actual inflow angle and an induced pitch from the root of the rear propeller blade to any cross section of the blade are obtained, which are recorded as the actual inflow angle and the induced pitch of the rear propeller;

[0012] The resultant speed of the rear propeller is obtained according to the induced speed of the front propeller, the actual inflow angle of the rear propeller, the inter-propeller spacing factor and the inter-propeller blocking factor;

[0013] The chord length of the rear propeller is obtained according to the combined speed of the rear propeller, and the rotation angle of the rear propeller is obtained according to the actual inflow angle of the rear propeller. The chord length of the rear propeller and the rotation angle of the rear propeller are aerodynamic shape indicators of the rear propeller of the coaxial counter-rotating propeller.

[0014] The front propeller force distribution curve and the rear propeller force distribution curve are given identical force distribution curves.

[0015] The basic data of the coaxial counter-rotating propeller include: the flight speed of the coaxial counter-rotating propeller, the altitude of the coaxial counter-rotating propeller, the radius of a single propeller blade, the number of blades of the coaxial counter-rotating propeller, the rotation speed of the coaxial counter-rotating propeller, the design thrust of the coaxial counter-rotating propeller, the lift coefficient corresponding to the maximum lift-to-drag ratio, the drag coefficient, the angle of attack and the blade element size; the blade element size includes: the actual calculation range of the blade radius and the number of blade element sections.

[0016] The actual inflow angle of the front propeller and the induced pitch of the front propeller are solved by combining the following equations using the Newton iteration method. The calculation formula is as follows:

[0017]

[0018] in, is the actual inflow angle of the front propeller, V 0 is the flight speed of the coaxial counter-rotating propeller, V′ is the induced pitch of the front propeller, Ω is the rotation speed of the coaxial counter-rotating propeller, r is the distance from the root of the front propeller blade to any section of the blade, is any value in the front propeller force distribution curve, N b is the number of blades of the coaxial counter-rotating propeller, R is the radius of a single propeller blade, and ρ is the air density.

[0019] The induced speed of the front propeller is calculated according to the actual inflow angle of the front propeller and the induced pitch of the front propeller. The calculation formula is as follows:

[0020]

[0021] in, is the actual inflow angle of the front propeller, V′ is the induced pitch of the front propeller, V a is the induced velocity in the axial direction, Vt is the induced velocity in the annular direction.

[0022] The inter-propeller spacing factor represents the influence of the spacing between the front propeller and the rear propeller, and the inter-propeller blocking factor represents the influence of the slipstream blocking between the propellers. The value range of the inter-propeller spacing factor is 0 to 1, and the value range of the inter-propeller blocking factor is 0 to 1.

[0023] The actual inflow angle of the rear propeller and the induced pitch of the rear propeller are solved by combining the following equations using the Newton iteration method. The calculation formula is as follows:

[0024]

[0025] in, is the actual inflow angle of the rear propeller, V 0 is the flight speed of the coaxial counter-rotating propeller, V” is the induced pitch of the rear propeller, λ is the pitch factor between propellers, τ is the blocking factor between propellers, Ω is the rotation speed of the coaxial counter-rotating propeller, r’ is the distance from the root of the rear propeller blade to any section of the blade, V t is the induced velocity in the annular direction, V a is the induced axial velocity, is any value in the rear propeller force distribution curve, N b is the number of blades of the coaxial counter-rotating propeller, R is the radius of a single propeller blade, and ρ is the air density.

[0026] The combined speed of the rear propeller is obtained according to the induced speed of the front propeller, the actual inflow angle of the rear propeller, the pitch factor between propellers and the blocking factor between propellers, and the calculation formula is as follows:

[0027]

[0028] Where W' is the combined speed of the rear propeller, Ω is the rotation speed of the coaxial counter-rotating propeller, r' is the distance from the root of the rear propeller blade to any section of the blade, V t is the induced velocity in the annular direction, V a is the induced axial velocity, λ is the propeller spacing factor, τ is the propeller blocking factor, is the actual inflow angle of the rear propeller, V 0 is the flight speed of the coaxial counter-rotating propellers, and V” is the induced pitch of the rear propeller.

[0029] According to the combined speed of the rear propeller, the chord length of the rear propeller is obtained, and according to the actual inflow angle of the rear propeller, the rotation angle of the rear propeller is obtained, and the calculation formula is as follows:

[0030]

[0031] Where, b' is the chord length of the rear propeller, W' is the resultant speed of the rear propeller, ρ is the air density, is the actual inflow angle of the rear propeller, Cl is the lift coefficient corresponding to the maximum lift-to-drag ratio, C d is the drag coefficient, θ' is the rotation angle of the rear propeller, and α is the angle of attack of the coaxial counter-rotating propeller.

[0032] In a second aspect, the present application proposes a computer program product, including a computer program or instructions, which, when executed by a processor, implements the method for designing the aerodynamic shape of a coaxial counter-rotating propeller based on tension distribution.

[0033] Beneficial technical effects:

[0034] The present application proposes a method for designing the aerodynamic shape of a coaxial counter-rotating propeller based on tension distribution. The aerodynamic shape of the front and rear propellers is designed by using the tension distribution curves of the given front and rear propellers along the span direction of the blades. The front propeller is designed according to the design method of a single propeller, and the design of the rear propeller needs to consider the influence of the induced velocity of the front propeller and the axial spacing between the front and rear propellers. The influence of the axial spacing is achieved by introducing an inter-propeller spacing factor and an inter-propeller blocking factor. Experiments have proved that the method of the present application is effective and improves the design accuracy of the aerodynamic shape design of the coaxial counter-rotating propeller. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 Flow chart of the aerodynamic shape design method of coaxial counter-rotating propellers based on tension distribution according to an embodiment of the present application;

[0036] Figure 2 A schematic flow chart of a method for designing aerodynamic shape of coaxial counter-rotating propellers based on tension distribution according to an embodiment of the present application;

[0037] Figure 3 The angle curve of the relative position of the embodiment of the present application;

[0038] Figure 4 The chord length curve of the relative position of the embodiment of the present application. DETAILED DESCRIPTION

[0039] The specific implementation of the present application is further described in detail below in conjunction with the drawings and examples.

[0040] Embodiment 1:

[0041] This embodiment proposes a method for designing the aerodynamic shape of a coaxial counter-rotating propeller based on the force distribution. Figure 1 , Figure 2 As shown, including:

[0042] Step S1: obtaining a front propeller thrust distribution curve and a rear propeller thrust distribution curve of a coaxial counter-rotating propeller;

[0043] In this embodiment, the front propeller force distribution curve and the rear propeller force distribution curve are given the same force distribution curve

[0044] The form is as follows:

[0045]

[0046] Among them, B 0 ~B 9 are constant coefficients, respectively: B 0 =377.33924,B 1 =-12607.73068,B 2 =155886.47984,B 3 =-970685.89712,B 4 =3750031.98714,B 5 =-9216045.91951,B 6 =1.43468×10 7 ,B 7 =-1.36564×10 7 ,B 8 =7237425.9308,B 9 =-1634584.58835.

[0047] Step S2: determining basic data of the coaxial counter-rotating propeller according to the design requirements of the coaxial counter-rotating propeller;

[0048] In this embodiment, step S1 and step S2 are in no particular order, and the basic data of the coaxial counter-rotating propeller include: the flight speed V of the coaxial counter-rotating propeller 0 , the altitude H of the coaxial counter-rotating propeller, the radius R of a single propeller blade, the number N of blades of the coaxial counter-rotating propeller b , the rotation speed of the coaxial counter-rotating propeller Ω, the design thrust of the coaxial counter-rotating propeller T, and the lift coefficient C corresponding to the maximum lift-to-drag ratio l , drag coefficient C d , angle of attack α and blade element size; the blade element size includes: the actual calculation range of blade radius and the number of blade element segments, as shown in Table 1:

[0049] Table 1 Basic data

[0050]

[0051] Step S3: According to the front propeller force distribution curve and basic data, the actual inflow angle and induced pitch from the root of the front propeller blade to any cross section of the blade are obtained, which are recorded as the actual inflow angle and induced pitch of the front propeller;

[0052] The actual inflow angle of the front propeller and the induced pitch of the front propeller are solved by the Newton iteration method by combining the following equations. The calculation formula is as follows:

[0053]

[0054] in, is the actual inflow angle of the front propeller, V 0 is the flight speed of the coaxial counter-rotating propeller, V′ is the induced pitch of the front propeller, Ω is the rotation speed of the coaxial counter-rotating propeller, r is the distance from the root of the front propeller blade to any section of the blade, is any value in the front propeller force distribution curve, N b is the number of blades of the coaxial counter-rotating propeller, R is the radius of a single propeller blade, and ρ is the air density.

[0055] The air density can be calculated from the altitude H of the coaxial counter-rotating propeller using the following formula:

[0056]

[0057] Step S4: according to the actual inflow angle of the front propeller and the induced pitch of the front propeller, the aerodynamic shape of the front propeller of the coaxial counter-rotating propeller is obtained according to the design method of a single propeller;

[0058] Specifically: the resultant velocity W is obtained through geometric conditions, and the chord length b of the front propeller and the rotation angle θ of the front propeller at the section at r are solved;

[0059] Total speed W:

[0060]

[0061] Chord length b:

[0062]

[0063] Angle θ:

[0064]

[0065] Where W is the combined speed of the front propeller, Ω is the rotation speed of the coaxial counter-rotating propeller, r is the distance from the root of the front propeller blade to any section of the blade, is the actual inflow angle of the front propeller, V 0 is the flight speed of the coaxial counter-rotating propeller, V′ is the induced pitch of the front propeller, b is the chord length of the front propeller, and θ is the rotation angle of the front propeller.

[0066] Among them, the chord length b of the front propeller and the rotation angle θ of the front propeller are the aerodynamic shape indicators of the front propeller.

[0067] In this embodiment, the integral of the overall pulling force T and the torque M of the blade is calculated and the total efficiency η of the front propeller is solved, so as to check whether the obtained chord length b of the front propeller and the rotation angle θ of the front propeller meet the design requirements.

[0068] Overall pulling force of blade T:

[0069]

[0070] Torque M:

[0071]

[0072] The total efficiency of the front propeller η:

[0073]

[0074] Among them, R min is the minimum radius of a single propeller blade, R max is the maximum radius of a single propeller blade.

[0075] The solution of integrating the front blade element is that the overall blade tension T = 960.3N and torque M = 216.4Nm, and the total efficiency of the front blade is η = 0.8681.

[0076] Step S5: The induced speed of the front propeller is calculated according to the actual inflow angle of the front propeller and the induced pitch of the front propeller. The calculation formula is as follows:

[0077]

[0078] in, is the actual inflow angle of the front propeller, V′ is the induced pitch of the front propeller, V a is the induced velocity in the axial direction, V t is the induced velocity in the annular direction.

[0079] Step S6: according to the rear propeller thrust distribution curve, basic data, the induced speed of the front propeller, the inter-propeller spacing factor and the inter-propeller blocking factor, the actual inflow angle and induced pitch of the rear propeller from the root of the rear propeller blade to any cross section of the blade are obtained, which are recorded as the actual inflow angle and induced pitch of the rear propeller;

[0080] In this embodiment, according to the tension distribution and design state, the induced speed of the front propeller, the influence of the front and rear propeller spacing and the influence of the slip flow blockage between the propellers are quantified as the inter-propeller spacing factor λ and the inter-propeller blockage factor τ, and the simultaneous equations in the calculation of the rear propeller are taken into account to solve the actual inflow angle of the cross section at the rear propeller r' by the Newton iteration method. and induced pitch V", wherein the inter-propeller spacing factor represents the influence of the spacing between the front propeller and the rear propeller, the inter-propeller blocking factor represents the influence of the slipstream blocking between the propellers, the inter-propeller spacing factor ranges from 0 to 1, and the inter-propeller blocking factor ranges from 0 to 1.

[0081] The actual inflow angle of the rear propeller and the induced pitch of the rear propeller are solved by combining the following equations using the Newton iteration method. The calculation formula is as follows:

[0082]

[0083] in, is the actual inflow angle of the rear propeller, V 0 is the flight speed of the coaxial counter-rotating propeller, V” is the induced pitch of the rear propeller, λ is the pitch factor between propellers, τ is the blocking factor between propellers, Ω is the rotation speed of the coaxial counter-rotating propeller, r’ is the distance from the root of the rear propeller blade to any section of the blade, V t is the induced velocity in the annular direction, V a is the induced axial velocity, is any value in the rear propeller force distribution curve, N b is the number of blades of the coaxial counter-rotating propeller, R is the radius of a single propeller blade, and ρ is the air density.

[0084] Step S7: obtaining a combined speed of the rear propeller according to the induced speed of the front propeller, the actual inflow angle of the rear propeller, the inter-propeller spacing factor, and the inter-propeller blocking factor;

[0085] The combined speed of the rear propeller is obtained according to the induced speed of the front propeller, the actual inflow angle of the rear propeller, the pitch factor between propellers and the blocking factor between propellers, and the calculation formula is as follows:

[0086]

[0087] Where W' is the combined speed of the rear propeller, Ω is the rotation speed of the coaxial counter-rotating propeller, r' is the distance from the root of the rear propeller blade to any section of the blade, V t is the induced velocity in the annular direction, V a is the induced axial velocity, λ is the propeller spacing factor, τ is the propeller blocking factor, is the actual inflow angle of the rear propeller, V 0 is the flight speed of the coaxial counter-rotating propellers, and V” is the induced pitch of the rear propeller.

[0088] Step S8: According to the combined speed of the rear propeller, the chord length of the rear propeller is obtained, and according to the actual inflow angle of the rear propeller, the rotation angle of the rear propeller is obtained. The chord length of the rear propeller and the rotation angle of the rear propeller are aerodynamic shape indicators of the rear propeller of the coaxial counter-rotating propeller.

[0089] According to the combined speed of the rear propeller, the chord length of the rear propeller is obtained, and according to the actual inflow angle of the rear propeller, the rotation angle of the rear propeller is obtained, and the calculation formula is as follows:

[0090]

[0091] Where, b' is the chord length of the rear propeller, W' is the resultant speed of the rear propeller, ρ is the air density, is the actual inflow angle of the rear propeller, C l is the lift coefficient corresponding to the maximum lift-to-drag ratio, C d is the drag coefficient, θ' is the rotation angle of the rear propeller, and α is the angle of attack of the coaxial counter-rotating propeller.

[0092] Similarly, the integral of the overall pulling force T and torque M of the blade is calculated and the total efficiency η of the rear propeller is solved to check whether the chord length b' of the rear propeller and the rotation angle θ' of the front propeller meet the design requirements:

[0093] Overall pulling force of blade T:

[0094]

[0095] Torque M:

[0096]

[0097] Total efficiency of rear propeller η:

[0098]

[0099] The solution of integrating the rear blade element is that the overall blade tension T = 960.3N and torque M = 212.5Nm, and the total efficiency of the rear blade is η = 0.8843.

[0100] like Figure 3 , Figure 4 As shown in the figure, the corresponding relationship between the relative position of the front propeller of the propeller calculated in this embodiment and the angle and chord length is shown. It can be found that the calculation result of the blade angle is highly consistent with the experimental data, and the corresponding relationship between the blade chord length and the relative position is good. Within the error range, it can be considered that this program has high accuracy and reliability in the design calculation of a single propeller. It can be seen that the method of this embodiment is effective. The induced speed of the front propeller is calculated by the actual inflow angle of the front propeller and the induced pitch of the front propeller, and the inter-propeller spacing factor and the inter-propeller blocking factor are introduced to obtain the aerodynamic shape index of the rear propeller of the coaxial counter-rotating propeller. The above method improves the design accuracy of the aerodynamic shape design of the coaxial counter-rotating propeller.

[0101] Embodiment 2:

[0102] This embodiment proposes a computer program product, including a computer program or instructions, which, when executed by a processor, implements the method for dynamic prediction and multi-strategy configuration of online car-hailing boarding points.

[0103] Based on such understanding, the technical solution of the present application, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a computer program product.

[0104] The various embodiments in the present application are described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.

[0105] The protection scope of the present application is not limited to the above-mentioned embodiments. Obviously, those skilled in the art can make various changes and modifications to the present disclosure without departing from the scope and spirit of the present disclosure. If these changes and modifications fall within the scope of the claims of the present disclosure and their equivalents, the intention of the present disclosure also includes these changes and modifications.

Claims

1. A method for designing aerodynamic shape of coaxial counter-rotating propellers based on tension distribution, characterized in that: include: Obtaining a front propeller thrust distribution curve and a rear propeller thrust distribution curve of a coaxial counter-rotating propeller; Determine the basic data of the coaxial counter-rotating propeller according to the design requirements of the coaxial counter-rotating propeller; According to the front propeller thrust distribution curve and basic data, the actual inflow angle and induced pitch from the root of the front propeller blade to any section of the blade are obtained, which are recorded as the actual inflow angle and induced pitch of the front propeller; According to the actual inflow angle of the front propeller and the induced pitch of the front propeller, the aerodynamic shape of the front propeller of the coaxial counter-rotating propeller is obtained according to the design method of a single propeller. The induced speed of the front propeller is calculated based on the actual inflow angle of the front propeller and the induced pitch of the front propeller; According to the rear propeller thrust distribution curve, basic data, the induced speed of the front propeller, the inter-propeller spacing factor, and the inter-propeller blocking factor, an actual inflow angle and an induced pitch from the root of the rear propeller blade to any cross section of the blade are obtained, which are recorded as the actual inflow angle and the induced pitch of the rear propeller; The resultant speed of the rear propeller is obtained according to the induced speed of the front propeller, the actual inflow angle of the rear propeller, the inter-propeller spacing factor and the inter-propeller blocking factor; The chord length of the rear propeller is obtained according to the combined speed of the rear propeller, and the rotation angle of the rear propeller is obtained according to the actual inflow angle of the rear propeller. The chord length of the rear propeller and the rotation angle of the rear propeller are aerodynamic shape indicators of the rear propeller of the coaxial counter-rotating propeller.

2. The method for designing aerodynamic shape of coaxial counter-rotating propellers based on tension distribution according to claim 1, characterized in that: include: The front propeller force distribution curve and the rear propeller force distribution curve are given identical force distribution curves.

3. The method for designing aerodynamic shape of coaxial counter-rotating propellers based on tension distribution according to claim 1, characterized in that: The basic data of the coaxial counter-rotating propeller include: the flight speed of the coaxial counter-rotating propeller, the altitude of the coaxial counter-rotating propeller, the radius of a single propeller blade, the number of blades of the coaxial counter-rotating propeller, the rotation speed of the coaxial counter-rotating propeller, the design thrust of the coaxial counter-rotating propeller, the lift coefficient corresponding to the maximum lift-to-drag ratio, the drag coefficient, the angle of attack and the blade element size; the blade element size includes: the actual calculation range of the blade radius and the number of blade element sections.

4. The method for designing aerodynamic shape of coaxial counter-rotating propellers based on tension distribution according to claim 1, characterized in that: The actual inflow angle of the front propeller and the induced pitch of the front propeller are solved by combining the following equations using the Newton iteration method. The calculation formula is as follows: in, is the actual inflow angle of the front propeller, V0 is the flight speed of the coaxial counter-rotating propeller, V′ is the induced pitch of the front propeller, Ω is the rotation speed of the coaxial counter-rotating propeller, r is the distance from the root of the front propeller blade to any section of the blade, is any value in the front propeller force distribution curve, N b is the number of blades of the coaxial counter-rotating propeller, R is the radius of a single propeller blade, and ρ is the air density.

5. The method for designing aerodynamic shape of coaxial counter-rotating propellers based on tension distribution according to claim 1, characterized in that: The induced speed of the front propeller is calculated according to the actual inflow angle of the front propeller and the induced pitch of the front propeller. The calculation formula is as follows: in, is the actual inflow angle of the front propeller, V′ is the induced pitch of the front propeller, V a is the induced velocity in the axial direction, V t is the induced velocity in the annular direction.

6. The method for designing aerodynamic shape of coaxial counter-rotating propellers based on tension distribution according to claim 1, characterized in that: The inter-propeller spacing factor represents the influence of the spacing between the front propeller and the rear propeller, and the inter-propeller blocking factor represents the influence of the slipstream blocking between the propellers. The value range of the inter-propeller spacing factor is 0 to 1, and the value range of the inter-propeller blocking factor is 0 to 1.

7. The method for designing aerodynamic shape of coaxial counter-rotating propellers based on tension distribution according to claim 1, characterized in that: The actual inflow angle of the rear propeller and the induced pitch of the rear propeller are solved by combining the following equations using the Newton iteration method. The calculation formula is as follows: in, is the actual inflow angle of the rear propeller, V0 is the flight speed of the coaxial counter-rotating propeller, V” is the induced pitch of the rear propeller, λ is the inter-propeller spacing factor, τ is the inter-propeller blocking factor, Ω is the rotation speed of the coaxial counter-rotating propeller, r’ is the distance from the root of the rear propeller blade to any section of the blade, V t is the induced velocity in the annular direction, V a is the induced axial velocity, is any value in the rear propeller force distribution curve, N b is the number of blades of the coaxial counter-rotating propeller, R is the radius of a single propeller blade, and ρ is the air density.

8. The method for designing aerodynamic shape of coaxial counter-rotating propellers based on tension distribution according to claim 1, characterized in that: The combined speed of the rear propeller is obtained according to the induced speed of the front propeller, the actual inflow angle of the rear propeller, the pitch factor between propellers and the blocking factor between propellers, and the calculation formula is as follows: Where W' is the combined speed of the rear propeller, Ω is the rotation speed of the coaxial counter-rotating propeller, r' is the distance from the root of the rear propeller blade to any section of the blade, V t is the induced velocity in the annular direction, V a is the induced axial velocity, λ is the propeller spacing factor, τ is the propeller blocking factor, is the actual inflow angle of the rear propeller, V0 is the flight speed of the coaxial counter-rotating propeller, and V” is the induced pitch of the rear propeller.

9. The method for designing aerodynamic shape of coaxial counter-rotating propellers based on tension distribution according to claim 1, characterized in that: According to the combined speed of the rear propeller, the chord length of the rear propeller is obtained, and according to the actual inflow angle of the rear propeller, the rotation angle of the rear propeller is obtained, and the calculation formula is as follows: Where b' is the chord length of the rear propeller, W' is the resultant speed of the rear propeller, ρ is the air density, is the actual inflow angle of the rear propeller, C l is the lift coefficient corresponding to the maximum lift-to-drag ratio, C d is the drag coefficient, θ' is the rotation angle of the rear propeller, and α is the angle of attack of the coaxial counter-rotating propeller.

10. A computer program product comprising a computer program or instructions, characterized in that When the computer program or instruction is executed by a processor, the method for designing the aerodynamic shape of a coaxial counter-rotating propeller based on tension distribution as described in any one of claims 1 to 9 is implemented.

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